1. Field of the Invention
This invention relates to a process for directly soldering a difficultly solderable material such as glass or ceramics or metals such as silicon, germanium, or the like at a temperature lower than about 180.degree. C, and to a solder alloy therefor.
2. Description of the Prior Art
In the past it has been difficult to directly apply solder to a solid inorganic oxide product, such as glass, ceramics or metals with an oxide surface such as silicon, germanium, aluminum, titanium, zirconium, tantalum or the like. Applicant has found that a solder selected from a group of alloys consisting of Pb-Sn-Zn-Sb alloys and Pb-Sn-Zn-Sb-Al alloys will firmly adhere to difficultly solderable materials when applied under the influence of ultrasonic vibration.
Such a solder alloy and a soldering process thereof have been disclosed in U.S. patent application Ser. No. 91,208, filed on Nov. 19, 1970 entitled "Process for Soldering Difficultly Solderable Metals such as Si, Ge, Al, Ti, Zr and Ta", now U.S. Pat. No. 3,744,121.
These types of special alloy solders for soldering ceramics are applicable in a temperature range of 200.degree.-350.degree. C which are relatively low temperatures. However, when these types of solders have been used for soldering electric or electronic components, the quality of the electric or electronic components obtained has decreased. For example, if a glass bulb of a vidicon, which is a type of camera tube, is soldered to a glass face plate, it is necessary to solder at a temperature lower than about 180.degree. C.
A need, therefore, exists for a process for the direct soldering of materials which have oxide surfaces at temperatures lower than about 180.degree. C.